Plasma structures observed in gas breakdown using a 1.5 MW, 110 GHz pulsed gyrotron

被引:92
作者
Hidaka, Yoshiteru [1 ]
Choi, E. M. [1 ]
Mastovsky, I. [1 ]
Shapiro, M. A. [1 ]
Sirigiri, J. R. [1 ]
Temkin, R. J. [1 ]
Edmiston, G. F. [2 ]
Neuber, A. A. [2 ]
Oda, Y. [3 ]
机构
[1] MIT, Plasma Sci & Fus Ctr, Cambridge, MA 02139 USA
[2] Texas Tech Univ, Ctr Pulsed Power & Power Elect, Dept Elect & Comp Engn, Lubbock, TX 79409 USA
[3] Japan Atom Energy Agcy, Naka Fus Res Inst, Naka, Ibaraki 3110196, Japan
关键词
electric breakdown; filamentation instability; gyrotrons; helium; nitrogen; plasma diagnostics; sulphur compounds; IONIZATION; DISCHARGE; MICROWAVE; INSTABILITY; FIELD; AIR;
D O I
10.1063/1.3083218
中图分类号
O35 [流体力学]; O53 [等离子体物理学];
学科分类号
070204 ; 080103 ; 080704 ;
摘要
Regular two-dimensional plasma filamentary arrays have been observed in gas breakdown experiments using a pulsed 1.5 MW, 110 GHz gyrotron. The gyrotron Gaussian output beam is focused to an intensity of up to 4 MW/cm(2). The plasma filaments develop in an array with a spacing of about one quarter wavelength, elongated in the electric field direction. The array was imaged using photodiodes, a slow camera, which captures the entire breakdown event, and a fast camera with a 6 ns window. These diagnostics demonstrate the sequential development of the array propagating back toward the source. Gases studied included air, nitrogen, SF6, and helium at various pressures. A discrete plasma array structure is observed at high pressure, while a diffuse plasma is observed at lower pressure. The propagation speed of the ionization front for air and nitrogen at atmospheric pressure for 3 MW/cm(2) was found to be of the order of 10 km/s.
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页数:7
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